Updated

Al-Jazeera TV broadcast an audiotape Thursday that was said to be the first released by the leader of Al Qaeda in Iraq, who succeeded the militant Abu Musab al-Zarqawi three months ago.

In the tape, Abu Hamza al-Muhajer said he was confident that victory will be achieved and called on all mujahedeen to unite on the battlefield, the station reported.

It played a brief excerpt from the tape, in which the speaker said, "Our enemy has unified its ranks against us. Isn't it time to get together, worshippers of God?"

CountryWatch: Iraq

Al-Muhajer, a previously unknown militant, became the leader of Iraq's most feared insurgent group after Zarqawi was killed in a U.S. airstrike June 7. Al-Muhajer was announced as Al Qaeda in Iraq's new leader on June 12 and received Usama bin Laden's endorsement in an audiotape from the Al Qaeda chief.

U.S. officials say they believe al-Muhajer is an Egyptian known as Abu Ayyoub al-Masri, an explosives expert who trained with Zarqawi in bin Laden's camps in Afghanistan.

In the first major attack claimed by the group under al-Muhajer, Al Qaeda in Iraq said it carried out the kidnapping and slaying of two American soldiers whose mutilated bodies were found in southern Baghdad on June 20.

Soon after he was named to his position, al-Muhajer issued a statement threatening horrific attacks "in the coming days" — but he issued no messages in his name since.

The U.S. military has put a $5 million bounty on al-Muhajer's head.

Click here to visit FOXNews.com's Iraq Center.